JPS58114305A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the wow and flutter of a reproduced sound signal, by eliminating the wow and flutter of a sound signal with a pilot signal which is separated from a signal modulated by a control signal. CONSTITUTION:A signal 30 modulated by a control signal is applied to a frequency divider 38 and a BBD39 via a zero-cross detector 36. The divided signals are supplied to clock driving circuits 42 and 43 via a PLL40 and a VCO41 respectively. Thus the clock pulses are generated in response to the wow and flutter to drive the BBDs39, 52 and 53. The output from which the wow and flutter of >=1Hz is eliminated by the BBD39 is fed to a clock driving circuit via a zero-cross detector 44, a PLL45 and a VCO58. The BBDs56 and 57 are driven by the output of the clock driving circuit. For sound signals 46 and 47, the wow and flutter of 1Hz is eliminated by LPFS350 and 51 and BBDs52 and 53 along with the wow and flutter of >=10Hz eliminated by the BBDs56 and 57 respectively and then delivered 67 and 68 via LPFs61 and 62.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing device, which modulates a pilot signal with a control signal, records a good signal on a control track, and separates the reproduced modulated wave signal and the pilot signal. By using this frequency fluctuation of the pilot signal to remove wow and flutter from the audio signal, the control signal and pilot signal can be recorded and played back on one track, and the wow and flutter from the reproduced audio signal can be removed. The purpose of the present invention is to provide a magnetic recording/reproducing device.

In a conventional video chip recorder, a control signal with an FR wave number of approximately 5OHH is recorded on a different track from the audio signal during recording, and during playback, the phase of the reproduced control signal is compared with a rotating drum pulse or a reference signal from a reference signal generator. to control the rotation of the cab stan motor.
In addition, the rotation speed of the capstan flywheel is detected from the signal from the PG transmitter, and the rotation of the capstan motor is controlled to prevent wow and flutter from being included in the reproduced audio signal. However, this rotational control of the capstan motor alone does not remove jitter sufficiently, and there is a drawback that the sound quality deteriorates due to jitter and flutter contained in the reproduced audio signal.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.

Figure jllH shows a block system diagram of one embodiment of the recording system of the apparatus of the present invention. In the figure, it is an input terminal to which a 1Fi Eirin signal is input, and this Eirin signal is supplied to the synchronization signal separation circuit 2. The horizontal synchronizing signal and vertical synchronizing signal extracted from the digital signal are supplied to the vertical synchronizing signal separating circuit 3, where the vertical synchronizing signal with a frequency of approximately @OHz as shown in the second figure is extracted. is separated and supplied to the splitter 4. The divider 4 divides this vertical synchronizing signal by 172 and converts it into a pulse with a frequency of approximately 30 Hz as shown in Fig. 2. Supply to T. Phase comparator? Fi voltage controlled oscillator (hereinafter referred to as ``vOo''), phase-locked loop (hereinafter referred to as ``PLL'') together with a branch gate.
The oscillation frequency is divided by RSS, and the output signal of 9 WOO16S 40 is compared in phase with the pulse of Htx, which has a frequency of about 3 (l). Yoshi frequency summary Hatake
Frequency synchronized with Hz pulse approximately 4.1.・kHz
The * pulse is taken out and supplied to the counting input terminal of counter 0. In addition, the mono-multi S is triggered by the rising edge of the pulse shown in figure M2) and generates the pulse shown in figure 1 (0), which is supplied to the reset terminal of counter 0, and the mono-multi is shown in figure 2. Triggered by the rising edge of the pulse (), a pulse-like control signal shown in FIG. 1(b) is generated and supplied to the modulator 11.

The counter 0 starts counting the pulses supplied from the VOOI at the time when the pulse shown in Figure 2 (0) from the monomulti 5 falls, and divides this pulse by /1.24 to count the pulses. A pulse (pilot signal) having a frequency of approximately 4 Hz as shown in FIG. 2 (7) is generated and supplied to the low-pass filter 12. At this point, you can adjust the monomulti 50 time constant to change the pulse width of the pulse shown in Figure 2 (0) or advance or retard the phase of the pulse shown in Figure 2 (7). be able to. The pulse shown in FIG.
The signal is supplied to the modulator 11 as a HIE sine wave. Modulator 11 #i Amplitude modulates this sine wave with a frequency of approximately 410 Hst using a monomulti 6 or higher pulse, as shown in Fig. 2 (7).
As shown in FIG. 1, a modulated wave having a frequency of approximately 4@OHa is generated and the amplitude is large during the low level period of the monomultiple pulse and small during the high level period, and this is supplied to the amplifier 1s. The phase of the modulated wave shown in Fig. 2 (7) can be changed by changing the time constant of the monomulti 20 at point a where it changes from large amplitude to small amplitude, and the time constant of monomulti 1 can be changed. By changing the pulse width shown in FIG. 2 (to), it is possible to change the phase of the pulse that changes from a small amplitude to a large amplitude, and the amplitude C in the modulator 11 can be made to an excessively loud level.

This modulated wave is amplified in an amplifier 13, then superimposed on a bias signal from a bias oscillator 1s in a mixer 14, and supplied to the magnetic head 1@, where it is recorded on a control track in the longitudinal direction of the magnetic tape ITO. Along with this, the first channel coming from the input terminal 111, 1/b,
The audio signals of the second channel are transmitted through amplifiers 111L and 111L, respectively.
11 and then superimposed on the bias signal from the bias oscillator 1i in mixers 20 & 201), respectively, to the magnetic head 21a.

HL) and are recorded on two audio tracks different from the control track in the longitudinal direction of the magnetic chip 17, respectively.

FIG. 3 shows a block system diagram of one embodiment of the reproduction system of the magnetic recording and reproduction apparatus according to the present invention. 5ori magnetic tag 1T
jl! played from the control track of Figure 2 (I
F) An input terminal into which a modulated wave as shown in K is input. This modulated wave is supplied to an automatic gain control (hereinafter referred to as GOJ) amplifier 31, where it is amplified while removing long-period level fluctuations. Demodulator S! is supplied to the demodulator 32 and limiter 33. The modulated wave is full-wave rectified and the fourth
The waveform shown in FIG. 2 is smoothed to obtain the waveform shown in FIG.

The zero cross detector 34 compares the waveform shown in FIG.
Detects the control signal shown in and outputs it to output terminal 3I.
Output. Here, there is a phase shift f between the detection point of the control signal and the amplitude change point a in FIG. 4 (4), which is the point where the control signal was generated during recording.
Since this phase shift is determined by the smoothing time constant of the demodulator I and the threshold level of the zero-cross detector 34 and is a constant value, highly accurate tracking can be performed as in the conventional case.

9, the modulated wave from the Go amplifier 31 is the limiter 13
After its amplitude is made constant, it is supplied to the zero cross detector S@, where it is converted into a pulse-like control signal that becomes high level above gv and low level below Ov, and is sent to terminal SW of switch aW.

and supplied to PIIa 37. PLL57H is set to follow the frequency fluctuation of the pulsed pilot signal supplied, and even if the pilot signal drops out, it continues to oscillate within the variable range of the built-in VaO and generates a dropped pulse. Output to terminal 8W2 of switch 8W. Switch 8W connects terminals sw and sw when there is no pilot signal dropout,
If there is a drop act, there is a switch that connects the terminals sw and sws. Through this switch SW, the pilot signal, which is made into a pulse with a frequency of about 4.Q Ha, is sent to the splitter sl and the packet brigade denoise (hereinafter referred to as It is supplied to 3@ (referred to as BBD J).

Frequency divider ■ divides the above pulse by 176 to give a frequency of approximately 1 @
It is supplied to PI, I, 40 as a pulse of Eml. Since it is difficult to detect low frequency fluctuations with a pilot signal having a frequency of approximately 480 Hg, the frequency is divided to a frequency of approximately 1@Hz. From a pulse with a frequency of approximately S.Hz, a frequency fluctuation of approximately 1H horse or more (wow/flutter) was detected at PLI, 40, and R in PLL4oo was detected.
As the p voltage change due to the Loog filter, *citLV
tL, 70041 supplied to QO41 changes the oscillation frequency of the base in accordance with the fluctuation and flutter. The large signal generated by this vao 41 is supplied to clock drive circuits 42 and 43, where it is waveform-shaped into a clock pulse for BBD. The clock drive circuits 42 and 48 have the same characteristics and cannot drive two BBDLs with one clock drive circuit, so two clock drive circuits are used.

If one clock drive circuit Fi can drive three BBDs, one clock drive circuit Fi is sufficient. The clock pulse obtained by the clock drive circuit 42 is supplied to BBDsl, and the BBDS
l is supplied to the zero-cross detector 44 after removing work and flutter of approximately IHM or higher from the pilot signal with a frequency of approximately 410 Hg including the work and flutter by varying its delay time, where it is first passed through a low-pass filter. After the clock component is removed by (not shown), the zero cross is detected, shaped into a pulse, and supplied to the PLL 4g.

9, the first input to input terminals 4'@ and 4F, respectively.
The input sensitivity of the channel and second channel audio signals is adjusted by variable resistors 4@ and 41, respectively, and the input sensitivity is adjusted by the low-pass filter s.
o and st, high-frequency components that cannot be transferred by BBD are removed, and BBDS2. Sarel supplied to S1. C(DBBDS2
．． It has the same number of stages as the 53flBID$1, and its delay time is varied by the clock pulse supplied from the □clock drive circuit 4s, and the 1st. The second channel audio signal is supplied to low-pass filters 54 and 55 after removing wow and flutter of approximately I Hg or more. 1st. The audio signals of the second channel are each passed through a low-pass filter s4゜5S.
The nine clock components mixed in by fiBBD52.51 are removed and supplied to BBDS1 and STK.

Here, the ninth step to remove the work and flutter of about I Hg or more is BBDSl,52,! 13 (It is necessary to widen the variable range of D delay g time, BIIDS@.

52, the delay time of $3 is set to be long. Therefore, for wow and flutter with a high frequency (for example, 1 g or more), the phase lag due to the delay becomes large and cannot be removed.

The pilot signal which is the output of ss, the first. The second channel audio signal similarly contains this high frequency flutter component.

Frequency path 4 whose low frequency fluctuations and flutter are removed by BBI) II and whose waveform is shaped by the zero cross detector 44
A HI Hz pilot signal is supplied to the FiPLL 41. A frequency fluctuation (flutter) of approximately 1.H8 or more is detected in the PLL 41 of this frequency path 4.Q Hz pulse, which is extracted as a voltage change by the loop filter built in the pLL 45 and supplied to voOI-. VOO
lg changes its oscillation frequency according to the flutter and supplies it to the clock drive circuit @O, where the waveform is shaped and the resulting clock pulse is BBD! ! @, IF
K is supplied. BBD51. SF has the same number of stages, 19~
This is considered to be the optimum delay time for removing SOHz flutter. BBDS@ and IT each vary the delay time using a clock pulse from the clock drive circuit layer O, and the first. 2nd channel audio signal 61t I@H2
+ flutter is removed and low-pass filter @1. Supply @2. 1st. The audio signals of the second channel are respectively low-pass filtered @1. After the clock component mixed in with BBDS@ and 5F is removed with @1, it is amplified with amplifier 6g and @4, and the output level is adjusted with variable resistors @S and @・, and output terminal sy
, @s] is output.

Here, there is a difference between the point 10 phase at which the modulated wave changes from large amplitude to small amplitude shown in Fig. 2 (F) during recording and the fluctuations and flutters included in the reproduced audio signal as shown in Fig. There is a relationship as shown below. Figure S shows that when the point where the large-amplitude sine wave shown in Figure 2 (7) takes its minimum value is the above-mentioned change point a, this phase is changed to This is a measurement of the wow and flutter contained in the audio signal. As is clear from Figure #!5, when the phase of change point 1 is approximately O, the wow and flutter is the least, and this change point 10 phase is the By changing the time constant of the monomulti S shown in FIG. 1, it can be made approximately O.

As described above, the magnetic recording/reproducing apparatus according to the present invention records an audio signal on an audio track in the longitudinal direction of a magnetic recording medium, and also records a control signal frequency generated from a control signal obtained from a direct synchronization signal of a video signal. A pilot signal with a frequency that is an integer multiple is used as a control signal]
The modulated wave is modulated to obtain a modulated wave, the modulated wave is recorded on a control track in the longitudinal direction of the magnetic recording medium that is different from the audio track, and the modulated wave reproduced from the control track is demodulated to obtain a control signal and the modulated wave is In order to separate the bilodge signal synchronized with the control signal from the modulated wave and detect the frequency fluctuation of this pilot signal to remove fluctuations and flutter contained in the audio signal reproduced from the audio track, conventional control signals are used. To record and reproduce a control signal and a pilot signal using a control track on which only a control signal was recorded and reproduced, and to obtain a distortion-free audio signal by removing wow and flutter, which cannot be removed conventionally, from the frequency fluctuation of this pilot signal. It is something that has the length to be able to do things.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram of one embodiment of the recording system of the apparatus of the present invention, FIG. 2) to V) are time charts showing signal waveforms of each part of the circuit shown in FIG. Reproduction ml! Block system diagram of the example, Fig. 4 (4) to (C)
Figure U is a time chart showing the signal waveforms of each part of the circuit shown in Figure 3. Figure S is a diagram showing the relationship between the phase of the point where the modulation signal changes from large amplitude to small amplitude and the nine wow and flutter that remains in the reproduced audio signal. be. ? , IIIL, 1-1), 30, 41
, 47--Input terminal, 2--Synchronization signal separation circuit, 3
...Vertical synchronization signal separation circuit, 4,1. II... Frequency divider, 5, 6... Mono multi, 7-... Phase comparator, I
, 41 , If・VOo, 1 @... counter, 1
1...Modulator? ! , $0. If. 54.55. @1. @2...Low pass filter, 13°B
BI Kame, 181),・3. @4...Amplifier, 14
, 211&. 20m)...Mixer, 1s...Bias oscillator, 1
6゜21a, ztb...magnetic head, IT...
Magnetic tape, 31...Mugo amplifier, 32...Bitonizer, 33...91 Ivy, $4. ll, 44... Yarocross detector, 37.40.45-PLL, $1.52
．． Is. 1@, IT/BBD, 42.48, @@-...Clock drive circuit, @1. @T... Output terminal.

Claims (2)

[Claims] (1) The audio signal is recorded on the audio track in the longitudinal direction of the magnetically recorded bird body, and the control signal obtained from the synchronous signal of the video signal is generated] A pilot signal whose frequency is an integral multiple of the frequency of the control signal is generated. is modulated by a cough control signal to obtain a modulated wave, the modulated wave is recorded on a control track in the longitudinal direction of the magnetic recording medium that is different from the audio track, and the pressure wave modulated wave is demodulated by being reproduced from the control track. At the same time, a control signal is obtained, and a pilot signal that is synchronized with the control signal is separated from the modulated wave, and the frequency fluctuation of the pilot signal is detected to detect the noise contained in the audio signal reproduced from the audio track. Magnetic recording and reproducing device characterized by eliminating flutter. (2) Gorges modulated wave F! , is obtained by amplitude modulating the pilot signal using the control, Claim fXJXt! Magnetic recording and reproducing device.